Why didn't Goku and Vegeta find the Kais when they were in Super Buu?

well Kid buu absorbed the kai's, became fat buu, fat buu split in two, evil buu consumed mr buu and became super buu, i supose they would be in fat buu;s head

I doubt it, because when Fat Buu was absorbed surely the Kais would have appeared inside Super Buu as well if what you argue is true. This a question I've wondered myself. There are two possible answers, either it's a plot error or it is because the Kais were absorbed so long ago they are completely integrated into Buu and hence no longer have physical form.